Method, device and computer program product for diagnosing an oxidation catalyst

Abstract

A method, a device and a computer program product for the diagnosis of an oxidation catalyst for the oxidation of NO into NO2 in a motor vehicle is provided. An exhaust gas aftertreatment system includes at least the aforementioned oxidation catalyst and a particulate filter and / or an NOx-reducing catalyst arranged downstream of the oxidation catalyst, and a predetermined quantity of a reducing agent is supplied to the exhaust system upstream of the oxidation catalyst, and the NOx content or NO2 content is measured downstream of the oxidation catalyst. The method includes measuring a first value for the NOx / NO2 content at a point in time before the reduction agent is supplied to the exhaust gas system, measuring a second value for the NOx / NO2 content at a point in time during the period when the reduction agent is supplied to the exhaust gas system, and comparing the aforementioned values, in conjunction with which an indication of the impaired function of the oxidation catalyst is obtained when the difference between the aforementioned measured values is less than a predetermined first value.

Description

BACKGROUND AND SUMMARY[0001]The present invention proposes a method for diagnosing the function of an oxidation catalyst, for the conversion of NO into NO2, during operation on board a vehicle, which oxidation catalyst is arranged in a vehicle containing an internal combustion engine which, during operation, emits exhaust gases to an exhaust gas aftertreatment system containing the aforementioned oxidation catalyst.[0002]The present invention also proposes an engine-driven vehicle containing an internal combustion engine which, during operation, emits exhaust gases to an exhaust gas aftertreatment system containing an oxidation catalyst for the oxidation of NO to NO2, an injection device for injection of a reducing agent into the exhaust gas aftertreatment system upstream of the oxidation catalyst, an NOx-reducing catalyst and / or particulate filter arranged downstream of the oxidation catalyst, a gas sensor arranged at least downstream of the oxidation catalyst and a control unit fo...

AI Technical Summary

Benefits of technology

The present invention proposes a method for diagnosing the function of an oxidation catalyst in a vehicle's exhaust system, which converts NO into NO2. This is important for controlling emissions of nitrogen oxides and particulate matters in the exhaust gas. The invention also proposes an engine-driven vehicle containing an oxidation catalyst, an injection device for injecting a reducing agent upstream of the catalyst, an NOx-reducing catalyst, and a gas sensor for recording signals from the gas sensor. The invention also includes a computer program for executing the method and a computer program for controlling the engine. Overall, the invention provides a better understanding and control of the oxidation catalyst in the exhaust system of vehicles.

Problems solved by technology

Because the exhaust gases contain oxygen, it is difficult to reduce the oxides of nitrogen with high selectivity.

At low loadings on the engine (e.g. urban driving or an unladed goods vehicle), the exhaust gas temperature will not be sufficient to maintain the NOx adsorber at the necessary temperature.

If the oxidation catalyst in the CRT for some reason has an impaired NO2 formation function, a reduced quantity of soot will be oxidized in the particulate filter, which means that there is a risk that the particulate filter may become overcharged and that a sufficiently high temperature in the particulate filter can give rise to a soot fire, which, thanks to the increased quantity of soot that is burnt, can develop to such an extent that the particulate filter can be damaged.

This is because of the rapidly increasing risk of a future soot fire damaging the particulate filter.

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